scholarly journals Intracellular calcium and adenosine 3′,5′-cyclic monophosphate as mediators of potassium-induced aldosterone secretion

1985 ◽  
Vol 228 (1) ◽  
pp. 69-76 ◽  
Author(s):  
I Kojima ◽  
K Kojima ◽  
H Rasmussen
Keyword(s):  
Arachidonic Acid ◽  
Cyclic Amp ◽  
Intracellular Calcium ◽  
Secretory Response ◽  
Ionophore A23187 ◽  
Small Decrease ◽  
Aldosterone Secretion ◽  
Cyclic Monophosphate ◽  
A Value ◽  
Glomerulosa Cells

We compared the action of K+ on aldosterone secretion from isolated bovine adrenal glomerulosa cells with that of ionophore A23187. Addition of either 50 nM-A23187 or 8 mM-K+ to perifused cells induces a similar initial aldosterone-secretory responses, and a similar sustained increases in Ca2+ entry. However, K+-induced secretion is more sustained than is A23187-induced secretion, even though each agonist appears to act by increasing Ca2+ entry into the cells. When [3H]inositol-labelled cells are stimulated by 8 mM-K+, a small decrease in phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] is observed. This decrease is not accompanied by an increase in inositol trisphosphate (InsP3) concentration. Also, if [3H]arachidonic acid-labelled cells are exposed to 8 mM-K+, there is no increase in [3H]diacylglycerol production. When [3H]inositol-labelled cells are stimulated by 50 nM-A23187, a small decrease in PtdIns(4,5)P2 is observed. This decrease is not accompanied by an increase in InsP3. The cyclic AMP content of K+-treated cells was approximately twice that in A23187-treated cells. If cells are perifused simultaneously with 50 nM-forskolin and 50 nM-A23187, the initial aldosterone-secretory response is similar to that induced by A23187 alone, and the response is sustained rather than transient, and is similar to that seen during perifusion of cells with 8 mM-K+. This dose of forskolin (50 nM) causes an elevation of cyclic AMP concentration in A23187-treated cells, to a value similar to that in K+-treated cells. These results indicate that, in K+-treated cells, a rise in cyclic AMP content serves as a positive sensitivity modulator of the Ca2+ message, and plays a key role in mediating the sustained aldosterone-secretory response.

scholarly journals Demonstration of calcium-dependent phospholipase A2 activity in membrane preparation of rabbit neutrophils. Absence of activation by fMet-Leu-Phe, phorbol 12-myristate 13-acetate and A-kinase

1988 ◽  
Vol 250 (2) ◽  
pp. 343-348 ◽  
Author(s):  
T Matsumoto ◽  
W Tao ◽  
R I Sha'afi
Keyword(s):  
Arachidonic Acid ◽  
Cyclic Amp ◽  
Phospholipase A2 ◽  
Kinase Inhibitor ◽  
Calcium Ionophore ◽  
Membrane Preparation ◽  
Free Calcium ◽  
Ionophore A23187 ◽  
Pla2 Activity ◽  
Intact Cells

The presence of a phospholipase A2 (PLA2) activity in rabbit neutrophil membrane preparation that is able to release [1-14C]oleic acid from labelled Escherichia coli has been demonstrated. The activity is critically dependent on the free calcium concentration and marginally stimulated by GTP gamma S. More than 80% of maximal activity is reached at 10 microM-Ca2+. The chemotactic factor, fMet-Leu-Phe, does not stimulate the PLA2 activity in this membrane preparation. Pretreatment of the membrane preparation, under various experimental conditions, or intact cells, before isolation of the membrane with phorbol 12-myristate 13-acetate (PMA), does not affect PLA2 activity. Addition of the catalytic unit of cyclic AMP-dependent kinase to membrane preparation has no effect on PLA2 activity. Pretreatment of the intact neutrophil with dibutyryl-cAMP before isolation of the membrane produces a small but consistent increase in PLA2 activity. The activity of PLA2 in membrane isolated from cells treated with the protein kinase inhibitor 1-(5-isoquinolinesulphonyl)-2-methyl piperazine dihydrochloride (H-7) is significantly decreased. Furthermore, although the addition of PMA to intact rabbit neutrophils has no effect on the release of [3H]arachidonic acid from prelabelled cells, it potentiates significantly the release produced by the calcium ionophore A23187. This potentiation is not due to an inhibition of the acyltransferase activity. H-7 inhibits the basal release of arachidonic acid but does not inhibit the potentiation by PMA. These results suggest several points. (1) fMet-Leu-Phe does not stimulate PLA2 directly, and its ability to release arachidonic acid in intact neutrophils is mediated through its action on phospholipase C. (2) The potentiating effect of PMA on A23187-induced arachidonic acid release is most likely due to PMA affecting either the environment of PLA2 and/or altering the organization of membrane phospholipids in such a way as to increase their susceptibility to hydrolysis. (3) The intracellular level of cyclic AMP probably does not directly affect the activity of PLA2.

scholarly journals Cyclic AMP-independent secretion of mucin by SW1116 human colon carcinoma cells. Differential control by Ca2+ ionophore A23187 and arachidonic acid

1992 ◽  
Vol 283 (2) ◽  
pp. 421-426 ◽  
Author(s):  
S Yedgar ◽  
O Eidelman ◽  
E Malden ◽  
D Roberts ◽  
R Etcheberrigaray ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Arachidonic Acid ◽  
Cyclic Amp ◽  
Colon Carcinoma ◽  
Human Colon ◽  
Carcinoma Cells ◽  
Ionophore A23187 ◽  
Mucin Secretion ◽  
Colon Carcinoma Cells ◽  
Human Colon Carcinoma

The regulation of mucin secretion by SW1116 human colon carcinoma cells has been studied using monoclonal antibody 19-9, which has previously been used to detect mucin in the serum of cancer and cystic fibrosis patients. We found that SW1116 cells constitutively secrete considerable amounts of mucin as the predominant glycoprotein. The secretion of mucin by these cells is independent of cyclic AMP levels, but can be further stimulated by the Ca2+ ionophore A23187. However, arachidonic acid and its metabolites inhibit mucin secretion. Electron microscope studies reveal that the mucin is located near the plasma membrane as well as in vesicular and lysosome-like structures. However, the secretion pathway of mucin is different than that of the lysosomal contents, since arachidonic acid, while inhibiting mucin secretion, actually activates the secretion of the lysosomal enzyme beta-glucuronidase. We suggest that the mechanism of mucin secretion by SW1116 cells occurs by a pathway different from common exocytosis, and possibly by more than one pathway. The response of mucin secretion by SW1116 cells to common secretagogues resembles that of epithelial cells obtained from cystic fibrosis patients. Thus SW1116 cells are an especially interesting system for studying processes related to pathological states associated with excessive constitutive secretion of mucin.

Involvement of arachidonic acid in the chloride secretory response of intestinal epithelial cells

1993 ◽  
Vol 264 (2) ◽  
pp. C446-C452 ◽  
Author(s):  
K. E. Barrett ◽  
T. D. Bigby
Keyword(s):  
Arachidonic Acid ◽  
Cell Function ◽  
Chloride Secretion ◽  
Secretory Response ◽  
Epithelial Cell Line ◽  
Intestinal Epithelial ◽  
T84 Cells ◽  
Cyclic Monophosphate ◽  
Calcium Dependent ◽  
Similar Dose

The inflammatory mediator, adenosine, induces chloride secretion from the human colonic epithelial cell line, T84, in a manner apparently independent of increases in adenosine 3',5'-cyclic monophosphate, guanosine 3',5'-cyclic monophosphate, or cytoplasmic Ca2+. This prompted a search for other messengers that might account for the secretory response. A possible role for arachidonic acid or a metabolite in the response to adenosine has been demonstrated 1) by showing a relationship between arachidonic acid mobilization and chloride secretion induced by the adenosine agonist 5'-(N-ethylcarboxamido)adenosine (NECA) and 2) by determining that exogenous arachidonic acid affects T84 cell function. Addition of NECA to T84 cells induces chloride secretion and release of radioactivity from cells preloaded with [3H]arachidonic acid with similar dose dependencies. The effect of NECA on chloride secretion is inhibited by the phospholipase A2 inhibitor 4-bromophenacyl bromide or the diglyceride lipase inhibitor RG80267 but is unaffected by inhibitors of lipoxygenase or cyclooxygenase. Arachidonic acid has a small but significant effect on chloride secretion when added alone to T84 cells and synergistically enhances, as does NECA, responses to calcium-dependent secretogogues. Thus receptor-stimulated release of arachidonic acid in T84 cells may provide a second-messenger system promoting chloride secretion, in addition to calcium and cyclic nucleotides.

Angiotensin-mediated calcium efflux from adrenal glomerulosa cells

1983 ◽  
Vol 245 (3) ◽  
pp. E281-E287 ◽  
Author(s):  
R. Foster ◽  
H. Rasmussen
Keyword(s):  
Angiotensin Ii ◽  
Calcium Uptake ◽  
Initial Increase ◽  
Calcium Efflux ◽  
Aldosterone Secretion ◽  
Precise Location ◽  
A Value ◽  
Aldosterone Production ◽  
Flow Through ◽  
Glomerulosa Cells

The effects of angiotensin II on efflux of radiocalcium and production of aldosterone from dispersed bovine adrenal glomerulosa cells were studied using a flow-through system. Concentrations of angiotensin II between 1.25 X 10(-10) and 1.25 X 10(-8) M were found to stimulate both radiocalcium efflux and the rate of aldosterone production. The increase in radiocalcium efflux occurred within 1.5-2.5 min after angiotensin addition, reached a peak in 3.0-4.5 min, and then declined to a value slightly greater than control. The initial increase in aldosterone production occurred 3-5 min after the peak of calcium efflux. In cells preloaded with [45Ca] and then perfused for 1 h with a medium containing no calcium, the basal rate of aldosterone production fell to zero. Angiotensin II (1.25 X 10(-8) M) caused no increase in aldosterone secretion rate but still caused an efflux of radiocalcium. Exposure of cells to 5 X 10(-5) M verapamil blocked the effect of 1.25 X 10(-10) M angiotensin on both radiocalcium efflux and aldosterone production, but only partially blocked the effects of 1.25 X 10(-8) M angiotensin. In addition to stimulating calcium uptake into adrenal glomerulosa cells, angiotensin II stimulates the mobilization of calcium from an intracellular pool. The precise location of this pool is not known.

ANP-(7-23) stimulates a DHP-sensitive Ca2+ conductance and reduces cellular cAMP via a cGMP-independent mechanism

1992 ◽  
Vol 263 (2) ◽  
pp. C334-C342 ◽  
Author(s):  
C. M. Isales ◽  
J. A. Lewicki ◽  
J. J. Nee ◽  
P. Q. Barrett
Keyword(s):  
Low Dose ◽  
Cytosolic Calcium ◽  
Low Doses ◽  
Aldosterone Secretion ◽  
Cyclic Monophosphate ◽  
Low Concentrations ◽  
Independent Mechanism ◽  
Glomerulosa Cells ◽  
Anp Receptors ◽  
Low K

Atrial natriuretic peptide (ANP) potently inhibits aldosterone secretion from the adrenal glomerulosa cell. In many tissues ANP action is associated with an increase in cellular guanosine 3',5'-cyclic monophosphate (cGMP) mediated through binding of the peptide to one of its receptors [ANP-A(R1)]. However, in the adrenal glomerulosa cell, the physiological significance of this rise in cGMP content has been contested. In an effort to determine whether non-cyclase-containing ANP receptors, such as ANP-C(R2), are linked to any of the events triggered by ANP binding, we utilized a truncated ANP analogue, ANP-(7-23), which at low doses exhibits selectivity for the ANP-C(R2) receptor. With the use of bovine adrenal glomerulosa cells, low concentrations (1 nM) of ANP-(7-23) failed to stimulate cGMP production, did not lower cytosolic calcium in the presence of low K+, and did not inhibit aldosterone secretion. At 1 nM, however, the analogue decreased cellular adenosine 3',5'-cyclic monophosphate content [8.27 +/- 0.51 vs. 6.74 +/- 0.09 (SE) pmol/10(6) cells; P less than 0.02] and, only in the presence of high extracellular [K+], increased cytosolic calcium. This ANP-induced rise in cytosolic calcium was abolished by the addition of a low dose (30 nM) of the dihydropyridine nitrendipine. ANP-(7-23) when utilized at a higher concentration (500 nM) lost its selectivity for the ANP-R2 receptor and increased cellular cGMP content (control, 0.27 +/- 0.02 vs. 500 nM ANP-(7-23), 0.448 +/- 0.02 pmol/10(6) cells; P less than 0.01). At 500 nM, ANP-(7-23) also inhibited aldosterone secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of ANP on sustained aldosterone secretion stimulated by angiotensin II

1989 ◽  
Vol 256 (1) ◽  
pp. C89-C95 ◽  
Author(s):  
C. M. Isales ◽  
W. B. Bollag ◽  
L. C. Kiernan ◽  
P. Q. Barrett
Keyword(s):  
Steady State ◽  
Angiotensin Ii ◽  
Protein Phosphorylation ◽  
State Level ◽  
Secretory Response ◽  
Ionophore A23187 ◽  
Steady State Level ◽  
Ang Ii ◽  
Aldosterone Secretion ◽  
Influx Rate

The sustained aldosterone secretory response to angiotensin II (ANG II) depends on receptor-mediated increases in membrane diglyceride (DG) and an increase in calcium influx rate. These signals serve to activate membrane-associated protein kinase C (PKC) and result in enhanced phosphorylation of a unique set of proteins. These events can be mimicked by the addition of a phorbol ester, 12-O-tetra decanoyl phorbol 13-acetate (TPA), and a calcium ionophore, A23187, that bypass the initial receptor-associated events. We studied the inhibitory action of atrial natriuretic peptide (4-28 hANP) on the sustained secretory response to ANG II in isolated bovine adrenal glomerulosa cells. Although 10 nM ANP inhibited aldosterone secretion, it did not significantly alter the ANG II-elicited rise in 45Ca2+ influx rate [control (CON): 0.44 +/- 0.06; ANG II: 1.11 +/- 0.12 (P less than 0.001); ANG II + ANP: 1.18 +/- 0.14], the steady-state level of aequorin luminescence [intracellular [Ca2+] ([Ca2+]i)], or the rise in cellular DG content [CON: 0.132 +/- 0.01; ANG II: 0.194 +/- 0.01 (P less than 0.005); ANG II + ANP: 0.202 +/- 0.01 nmol/10(6) cells]. IN addition, ANP was able to inhibit aldosterone secretion stimulated by the combined addition of A23187 + TPA. When protein phosphorylation in the ANP-inhibited cells was evaluated, ANG II-induced protein phosphorylation events were preserved. In contrast to the effect of ANP, the calcium channel blocker nitrendipine abolished the ANG II-induced rise in 45Ca2+ influx rate, reduced the steady-state level of [Ca2+]i, and returned the phosphoproteins to their control states.(ABSTRACT TRUNCATED AT 250 WORDS)

Excitation-secretion coupling: involvement of potassium channels in ACTH-stimulated rat adrenocortical cells

1989 ◽  
Vol 120 (3) ◽  
pp. 409-421 ◽  
Author(s):  
N. Gallo-Payet ◽  
M. D. Payet
Keyword(s):  
Cyclic Amp ◽  
Calcium Influx ◽  
Inositol Phosphate ◽  
Aldosterone Secretion ◽  
Tetraethylammonium Chloride ◽  
Steroid Secretion ◽  
Phosphate Accumulation ◽  
Low Concentrations ◽  
Inositol Phosphate Accumulation ◽  
Glomerulosa Cells

ABSTRACT The mechanism by which ACTH stimulates calcium influx and steroid secretion was studied using rat adrenal glomerulosa cells, which were either freshly isolated or maintained in primary culture for 3 days. The potassium channel blocker tetraethylammonium chloride (TEA) stimulated twofold both corticosterone and aldosterone secretion; this stimulation was lower than that induced by ACTH at low concentrations (10 pmol/l). However, TEA and ACTH induced similar increases in Ca2+ influx and inositol phosphate accumulation. The three responses (steroid secretion, calcium influx and inositol phosphate accumulation) induced by TEA or low concentrations of ACTH were blocked by CoCl2. The greater stimulatory effect on steroid secretion of 10 nmol ACTH/l was decreased but not blocked by CoCl2. These data further document the complex mechanism of action of ACTH. It is postulated that, at low concentrations, ACTH binds preferentially to the high-affinity site of its receptor, leading to calcium influx by depolarization of the membrane potential, and to steroid secretion predominantly through an inositol phosphate- and Ca2+-stimulated pathway and also a cyclic AMP pathway. At higher concentrations, the hormone also binds to the low-affinity site of its receptor, largely stimulating cyclic AMP production and further increasing steroid secretion. Journal of Endocrinology (1989) 120, 409–421

scholarly journals Regulation of Arachidonic Acid Production by Intracellular Calcium in Parathyroid Cells: Effect of Extracellular Phosphate

2002 ◽  
Vol 13 (3) ◽  
pp. 693-698 ◽  
Author(s):  
Yolanda Almadén ◽  
Antonio Canalejo ◽  
Evaristo Ballesteros ◽  
Gracia Añón ◽  
Sagrario Cañadillas ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Intracellular Calcium ◽  
Intracellular Signaling ◽  
Calcium Level ◽  
Parathyroid Tissue ◽  
Ionophore A23187 ◽  
Calcium Receptor ◽  
Intracellular Calcium Level ◽  
High Phosphate ◽  
Stimulation Of

ABSTRACT. The action of extracellular calcium on the calcium receptor in parathyroid cells results in activation of phospholipase C (PLC), PLD, and PLA2. The PLA2-arachidonic acid (AA) intracellular signaling pathway mediates inhibition of parathyroid hormone (PTH) secretion. In addition, stimulation of the calcium receptor produces increases in intracellular calcium levels. It was demonstrated that high extracellular phosphate levels reduce the production of AA, a mechanism by which phosphate may stimulate PTH secretion. The objective was to determine, in parathyroid tissue, whether AA production is stimulated by increases in intracellular calcium levels and to investigate whether the decreased AA production induced by high extracellular phosphate levels could be modified by increases in intracellular calcium levels. Experiments were performed in vitro using parathyroid tissue. The intracellular calcium level was increased by incubation with an ionophore (A23187), which increases calcium influx across the cell membrane, or thapsigargin, which releases calcium from intracellular stores. The phosphate concentration in the medium was normal (1 mM) or high (4 mM). The response to calcium was evaluated by incubation with 0.6 or 1.35 mM calcium concentrations. AA production by parathyroid tissue was measured by gas chromatography. In parathyroid tissue incubated with either a calcium ionophore or thapsigargin, there was an increase in AA production, together with inhibition of PTH secretion, suggesting that PLA2 is activated by the elevation in intracellular calcium levels. Therefore, the effect of intracellular calcium level elevation on AA production in the presence of high extracellular phosphate levels was evaluated. The results demonstrate that, despite high phosphate levels in the medium, both the ionophore and thapsigargin were capable of inducing a marked increase in AA production, which was associated with a decrease in PTH secretion. In conclusion, in parathyroid tissue, AA levels can be regulated by an ionophore and thapsigargin, both of which increase cytosolic calcium concentrations. The stimulation of PTH secretion by high phosphate levels can be prevented by increases in intracellular calcium levels.

Sign in / Sign up

Export Citation Format

Share Document